21171533760 has 560 divisors, whose sum is σ = 82189600416. Its totient is φ = 5141864448.

The previous prime is 21171533671. The next prime is 21171533771. The reversal of 21171533760 is 6733517112.

21171533760 is a `hidden beast` number, since 2 + 117 + 1 + 533 + 7 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 27967302 + ... + 27968058.

Almost surely, 2^21171533760 is an apocalyptic number.

21171533760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21171533760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41094800208).

21171533760 is an abundant number, since it is smaller than the sum of its proper divisors (61018066656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21171533760 is a wasteful number, since it uses less digits than its factorization.

21171533760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882 (or 863 counting only the distinct ones).

The product of its (nonzero) digits is 26460, while the sum is 36.

It can be divided in two parts, 21171 and 533760, that added together give a triangular number (554931 = T₁₀₅₃).

The spelling of 21171533760 in words is "twenty-one billion, one hundred seventy-one million, five hundred thirty-three thousand, seven hundred sixty".